| 摘要 |
PURPOSE:To enhance the single wavelength oscillation yield by constituting the manufacture from a process to form a pos. resist pattern in a diffraction grating forming part on the surface of a base board, a process to coat neg. resist over the whole surface, a process to remove the pos. resist pattern formed in the diffraction grating forming part on the surface of base board by photo-lithography method, and a process to form diffraction grating in the removed part, and thereby forming a diffraction grating with the phase partially shifted without generating level difference on the semiconductor base board. CONSTITUTION:After pos. resist a2 and neg. resist a3 are coated over the surface of an InP base board 1, a pattern of the neg. resist a3 on the diffraction grating forming part is formed. After the pos. resist a2 is exposed using the neg. resist a3 as a mask, neg. resist b5 is coated over the surface. Using a mask a6 only the pos. resist a2 is exposed, developed, and removed, and a nag. resist b5 thereon is also removed. After pos. resist b7 is coated over the surface, a pattern of diffraction grating is baked fast onto this pos. resist b7, and upon developing, the neg. resist b5 is exposed using this pattern as a mask followed by developing. After transcribing the patterns of neg. resist b5 and pos. resist b7 onto the InP base board 1, these resists b5, b7 are exfoliated. Thereby a phase shift part 10 is formed flat in the center of diffraction grating 9, which is free from unaligned part. Accordingly the single wavelength oscillation yield of this laser will be enhanced. |
